Valve for steam-engines



P. R. POSTER. VALVE POR STEAM ENGINES.

No. 476,457. Patented June '7, 1892.

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(No Model.) P' R' POSTER. 2Sheets-Shget 2. VALVE POR STEM ENGINES. No. 476,457. Patented June 7,1892.

nu noms Pneus nu., weno-ums., msmxm'au, n. z:A

ilrvrrnn Srarns PEROY R. FOSTER, OF

BUFFALO, NET/V YORK.

VALVE FOR STEAM-ENGNES.

SPECIFICATION forming part of Letters Patent No. 476,457, dated June 7', 1892.

Application led March 2, 1891.

To @ZZ whom it may concern.-

Beit known that I, PERCY R. FOSTER, a citizen of the United States,residin g at Buffalo, in the county of Erie and State ot' New York, have invented new and useful Improvements in Valves for Stea1n-Engines, of which the following is a specification.

This invention relates to that class of direct-actin g steam-engines which are provided with a main steam-valve, an auxiliary pistonvalve connected with the main valve and having a longitudinally-reciprocating and a transversely-oscillating movement, and a cam by which motion is imparted to the valves, the arrangement being such that the valves are partly actuated by mechanical means and partly by the steam-pressure applied to the piston-valve. Steam-engines of this kind are used, for instance, in steam-pumps.

The object of my invention is to produce a steam-engine of this character in which the principal actuating parts of the valve mechanism are arranged outside of the steam-chest, where they are easy of access, so that these parts can be readilylubricated, adjusted, and repaired.

In the accompanying drawings, consisting of two sheets, Figure l is a longitudinal sectional elevation of a direct-acting steam-engine provided with my improvements. Fig. 2 is a horizontal section through the steamchest in line :c so, Fig. 1. Fig. 8 is adetached elevation of the piston-valve. Fig. 4 is a detached horizontal section of the cylindrical steam-chest. Figs. 5 and 6 are vertical crosssections in line y y, Fig. l, showing the piston-valve in diterent positions. Fig. 7 is a cross-section in line a z, Fig. l. Figs. S and 9 are fragmentary sectional elevations of the shifting-cam and connecting parts for operating the piston-valve. Fig. l0 is a plan view ot' the cam whereby the piston valve is shifted.

Like letters of reference refer to like parts in the several figures.

A represents the steam-cylinder, B the piston, and h the piston-rod. The steam-cylinder is provided centrally on its upper side with an enlarge1nent'O,havinga iiat horizontal face c on its upper side, which forms a seat for the slide-valve D.

E represents the cylindrical steanrchest,

Serial No. 383,413. (No model.)

which is arranged parallel with the steam-cylinder and provided centrally on its under side with a rectangular steam chamber F, which surmounts the seat of the slide-valve and incloses the latter.

f f represent steam-ports leading from the steam -chamber F to opposite ends of the steam-cylinder, and f2 is the exhaust-chamberform ed between the steam-ports ff. The face of the slide-valve is provided with the usual exhaust cavity f3. The cylindrical steam-chest is provided in its lower side with an opening g, leading to the steam-chamber F.

G represents a piston valve whereby the slide-valve is moved. This piston-valve is composed of two cup-shaped heads g g', arranged in opposite ends of the cylindrical steam-chest, and two longitudinal bars g2 g3, connecting said heads.

7L 71 represent transverse bridge-pieces connecting the bars g2 g3 of the piston-valve and forming a transverse slot h between them. The slide-valve is provided on its upper side with a lug t', which is loosely arranged in the slot between the bridge-pieces 71l h. The pistonvalve is capable of both a longitudinalreciprocating and a transversely-oscillating movement in the steam chest. During the reciprocating movement the piston-valve carries the slide-valve with it; but its oscillating movement has no effect upon the slide-valve, owing to the slot h in the piston-valve, which is of suiiicient length transversely to allow the piston-valve to rock freely without disturbing the slide-valve.

J represents the steam-supply pipe, andy' the main steam-inlet passage connecting the steam-supply pipe with the steam-chest.

K K' represent front and rear steam-passages whereby steam is conducted to and from the ends of the steam-chest and behind the heads of the piston-valve. These steampassages are formed lengthwise in the side ot' the steam-chest and open with their inner ends into the central portion of the steamchest by openings Z Z', while the opposite ends of the steam-passages communicate with the end portions of the steam-chest'by openings m m.

'n represents an exhaust-passage opening with its upper end in the steam-chest between the front and rear steam-passages Z Z and IOO leading with its lower end into the exhaustch amber f2.

The outer side of the longitudinal connecting-bar g2 of the piston-valve bears firmly against the adjacent inner side of the steamchest.

o 0 represent front and rear steam-inlet ports extending through thebar g2 and adapted to register with the inner openings Z Z of the front and rear steam-passages, whereby steam is alternately admitted to opposite ends of the steam-chest.

1J p represent front and rear exhaustport cavities formed in the outer side of the bar g2 and adapted to alternately connect the inner openings of the steam-passages K K with the exhaust-opening.

The ports in the piston-valve and the openings in the steam-chest are so arranged with reference to each other that the front inletport registers with 'the inner opening ot the front steanipassage when the rear exhaustport connects the rear steam-passage with the exhaust-opening and the rear inlet-port registers with the inner opening of the rear steampassage when the front exhaust-port connects the inner opening of the front steam-passage with the exhaust-opening.

The connecting-bar g2 ot the piston-valve is wider than the opposite bar g3, so that it exposes a larger surface to the steam-pressure than the bar g3, which causes the steam in the steam-chest to exert a greater lateral pressure against the bar g2, whereby the latter is held firmly against the inner side of the steamchest and forms a tight partition between its inlet and exhaust ports and the exhaust and.

steam-passage openings formed in the steamchest.

q represents the valve-rod secured to the front head of the piston-valve and passing through the front head of the steam-chest. The front end of this valve-rod is guided in a standard Q, secured upon the main frame of the engine.

R represents a shifting-cam whereby a reciprocating and a rocking motion is imparted to the valve-rod q and the piston-valve secured thereto. This cam consists of a curved plate fr, provided with a slot o having two longitudinal parallel sides r2 r and oblique ends or cam-faces fr* ri, which are inclined in opposite directions.

S represents arock-pin secured to the front portion of the valve-rod and arranged with its free end in the slot 0^ of the cam. This pin is rocked by the oblique cam-faces engaging alternately against the pin, whereby the piston-valve and the steam-ports therein are transversely oscillated.

s s represent trunnions formed on opposite sides of the shifting-cam S and journaled transversely in the standard Q.

T represents a depending rock-arm whereby the shifting-cam is actuated. This rock-arm is secured with its upper end to the side of the shifting cam and is connected with its lower end by a link t to a sleeve t', secured to the piston-rod, whereby the movement of the latter is caused to operate the piston-valve through the medium of the shifting-cam.

In the position of the parts represented in Fig. l the piston has completed its forward stroke and the slide-valve cuts ott communication with the ends of the steam-cylinder. ln this position of the parts the rock-pin of the valve-rod bears against the longitudinal side r2 of the cam-slot, as represented in Fig. S, and the piston-valve has been turned and moved backward sufficiently to cause its front inletport to register with the front inlet-opening and admit steam to the front end of the steam-chest, while its exhaust-port connects its rear steam-passage with the exhaust-opening, as represented in Fig. 2. The steam in entering the front end of the steam-chest drives the piston-valve backward, thereby moving' the slide-valve backward and admitting steam to the front end of the steam-cylinder. This causes the main piston to move backward and the piston-rod ot the same to carry the rock-arm ot the shiftingcam along with it, thereby moving the shifting-cam forwardly in the direction of the arrow in Fig. l. Then the cam approaches the end of its forward movement, its inclined front face r engages against the depending pin of the valve-rod and shifts the latter to the opposite longitudinal side r3 of the cani-slot, as represented in Fig. 9, thereby turning the pistonvalve so that the rear inlet and exhaust ports of the latter are in line with the exhaustopening and the inner opening of the rear steam-passage. The shifting-cam in continuing its forward movement carries the depending pin of the valve-rod and piston-valve forward until the rear inlet and exhaust ports of the piston-valve register with the inner opening of the rear steam-passage and the exhaust-opening, thereby admitting steam to the rear end of the steam-chest. The steam in entering the rear end of the steam-chest causes the piston-valve to continue its forward movement independent of the shiftingcam until the slide-valve has been moved forward sufficiently to admit steam to the rear end of the steam-cylinder. ln this manner the piston-valve and slide-valve are actuated partly by mechanical means and partly by steam-pressure. The transversely-oscillating movement of the piston-valve and the first portion of the longitudinal movement of the same and of the slide-Valve are eiected by the shifting-cam and the last part of the longitudinal movement of both valves is effected by the steam-pressure.

By arranging the shifting-cam and the parts actuating the latter outside of the cylinder these parts can be readily lubricated and are easy of access in case they require to be adj usted or repaired.

I claim as my invention- The combination, with the steam cylinder' and piston, the steam-chamber, and cylindri- IOO IIC

@al steam-chest, of a slide-valve arranged in l to the piston-valve', when the stroke of both said steam-chamber, a piston-valve arranged valves is completed by the action of the steam in said steam-Chest and capable of a 1ongitudinal :reciprocating motion With the slide-- valve and a transverselyoscillating motion independent of the slideyalve, a Cain aetnated from the steam-piston and provided With two opposing oblique faces, and a projection on the valve-rod arranged between said faces, whereby the piston -valve is rst turned and then positively moved forward by one of the eani-faces until the steam-pressure is applied and the proj eetion on the valve-rod is thrown against the opposite earn-face, substantially as set forth.

W'itness my hand this 17 th day of February, 1891.

PERCY R. FOSTER.

Vitn esses:

THEO. L. PoPP, ALICE G. CONNELLY. 

